This invention relates to low temperature reactivated organochromium olefin polymerization catalysts.
Supported chromium-containing catalysts can be used to prepare olefin polymers in a hydrocarbon solution to give a product having excellent characteristics from many standpoints. Supported chromium-containing catalysts can also be used to prepare olefin polymers in a slurry system wherein the polymer is produced in the form of small particles of solid material suspended in the diluent. This process, frequently referred to as a particle-form process, has the advantage of being less complex. However, one method of controlling the molecular weight of the resulting polymer in the solution process is simply to vary the temperature, with lower molecular weight (higher melt flow) polymer being produced at the higher temperature. It is readily apparent that this type of process control is severely limited in a particle-form process since any substantial increase in temperature would cause the polymer to go into solution.